Every so often, we have some sporadic build issues that don't appear to

make much sense. Mostly it seems to be logging-related, with logged

output causing some blocked I/O issues. A possible culprit is the way we

initialize Review Board in our Sphinx extension.
This change updates that initialization to turn off logging, extensions,

and template management, with a hope that this will avoid any issues

that may be impacting Sphinx.
Doc-related URL settings now use https instead of http in places,

and some legacy imports have been removed.
Along with that, the release notes now include the manual's extension

for specialized references, so that the release notes can refer to

relevant sections in the manual.

Successfully built the manual and release notes.
Tested the references with the in-progress changes for 5.0.5 release

notes.